Guhring 9039190028450 Spiral Flute Tap 4-40 Unc 3 Flute

Product Description

The GUHRING 9039190028450 is a spiral flute tap designed for cutting internal threads in blind holes. Built from cobalt high-speed steel with a bright, uncoated finish, this tap handles alloyed and unalloyed steel in demanding threading applications. It cuts a 4-40 UNC right-hand thread to a 2B class of fit and is available in H2 and H3 thread limits. With a modified bottoming chamfer and a 40-degree helix angle, it pulls chips up and out of the hole efficiently, reducing the risk of chip packing in shallow or blind bores. Overall length is 1.882 inches. Installed by machinists and maintenance technicians working with small-diameter fastener patterns.

This tap is suited for threading blind holes in alloyed and unalloyed steel workpieces. The modified bottoming chamfer allows threading closer to the bottom of a hole than a standard plug or taper tap, making it a practical choice for tight-tolerance fixtures, instrument enclosures, and mechanical assemblies where thread depth is critical. The fast flute style promotes chip evacuation in through-spindle or hand-tapping setups. It is part of the GUHRING Series 3919 and is sold individually.

Key Features

• 4-40 UNC thread form, right-hand thread and right-hand flute direction
• Modified bottoming chamfer for threading near the bottom of blind holes
• Cobalt HSS construction for improved heat and wear resistance in steel
• 40-degree helix angle with fast flute style for efficient chip evacuation
• H2 and H3 thread limits, 2B class of fit for standard tolerance threading
• Bright, uncoated finish — no coating buildup concerns on small-diameter taps

Compatibility

Rated for use in alloyed and unalloyed steel. Designed for blind hole threading applications requiring a 4-40 UNC 2B thread form. Coolant-through is not supported on this tap.

Installation Notes

This tap is installed by machinists, toolroom technicians, or maintenance professionals using a tapping machine, CNC machining center, or hand tap wrench. Always ensure the workpiece is secured and the spindle is aligned to prevent tap breakage on small-diameter tooling. Power down and de-energize any machine before changing tooling. Follow standard shop practices for tap drill sizing to achieve the correct thread percentage before tapping.